Master Degree / Yüksek Lisans Tezleri
Permanent URI for this collectionhttps://hdl.handle.net/11147/3008
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Master Thesis Synthesis of Needle-Like and Rod-Like Nano Baco3 Particles(Izmir Institute of Technology, 2016) Kahyaoğlu, Tuğçe Nefise; Özdemir, EkremBarium carbonate (BaCO3) has been widely used in soft and heavy industries such as ferrite magnets, solid oxide fuel cells, optical glass manufacturing, coatings, and polymeric composite materials as well as ceramic and brick industries. Using BaCO3 in nano sizes will improve some of the physical properties of materials such as tensile strength, opacity, and thermal resistance. Production of BaCO3 by chemical method requires extensive crystallization times and higher temperatures. Production of BaCO3 by carbonation method usually yields particles with some agglomeration. In a study, conducted by our group funded by The Scientific and Technological Research Council (TUBITAK), a method was developed to synthesize hollow nano Calcium Carbonate (CaCO3) particles. It was aimed to apply the developed method, which is unique in its kind, to produce nano BaCO3 particles in different morphologies. Parameters such as effect of barium hydroxide (Ba(OH)2) concentration, CO2 flow rate, length in reaction chamber, and stirring rate were studied. Conductivity and pH values of the solution were monitored during crystallization. Surface morphology and crystal structure of the produced BaCO3 particles were characterized by Scanning Electron Microscopy (SEM) and X-Ray Diffraction (XRD), respectively. It was shown that rod-like BaCO3 particles produced in nano sizes with almost homogeneous size distributions. The rod-like BaCO3 particles had a diameter from 100 to 400 nm and an aspect ratio of about from 3 to 10. The produced rod-like nano BaCO3 were all in orthorhombic phase of BaCO3 called as Witherite.Master Thesis Investigation of the Reaction of Boron Oxide With Aluminium Powder and Method Development for Boron Determination in the Reaction Mixture(İzmir Institute of Technolog, 2007) Demirsar, Yelda; Özgen, TamerkanIn this study, a cheap method for the synthesis of elemental boron by the reduction of boron oxide with aluminum was investigated. However after various optimization studies, detectable boron amounts could not be found in the reaction mixtures by XRD and SEM-EDX analysis. Meanly aluminum borates were formed as products and these products were leached by 6 M HCl, however removel of borates could not be achieved. We think that the reason of this outcome is that we worked with simple experimental setup, therefore could not achieving the suitable experiment conditions and because of this we failed in the sythesis of boron. In the second part of the study, a new method for the direct determination of boron was investigated. 96 %pure boron and KBr were mixed and analyzed with Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS). No distinct differences for boron was observed in the DRIFT spectra. Then, different sample compositions were prepared with different amounts of boron and KBr. These samples were split as validation and calibration sets and their spectra were collected by DRIFTS. All collected spectral data were processed in a different computer where the data proccessing programs were installed. The genetic inverse least square (GILS) method was used inorder to generate calibration model. Results obtained showed that boron amounts could be directly determined with maximum 3-4 % error. Afterwards, same procedure was also tried for boron and boron oxide binary mixtures and boron, boron oxide and aluminum ternary mixtures. In the binary mixture, determination of boron could be successfully achieved, however boron oxide determination could not be achieved as good as boron determination. In the ternary mixture, better results were obtained compared to binary mixture. Finally, the method was tried with the original samples, but not very satisfactory results were obtained. We think this result is due to the malfunction of FTIR instrument and personal error in the preparation of similar samples. More sample preparation and measurement could not be achieved because the FTIR instrument is not functioning at present.